A PCR assay with high sensitivity and specificity for the detection of swine toxoplasmosis based on the GRA14 gene.

Toxoplasma gondii, an intracellular apicomplexan protozoan parasite, can infect all warm-blooded animals. Infected swine are considered one of the most important sources of T. gondii infection in humans. Rapidly and effectively diagnosing T. gondii infection in swine is essential. PCR-based diagnostic tests have been fully developed, and very sensitive and specific PCR is crucial for the diagnosis of swine toxoplasmosis. In this study, we used the T. gondii dense granule protein 14 (GRA14) gene as a target to design specific primers and established a high-specificity and high-sensitivity PCR detection method for swine toxoplasmosis. Notably, this PCR method could detect T. gondii tachyzoite DNA in the acute infection phase. The GRA14 gene PCR assay detected a minimum of 2.35 tachyzoites of T. gondii and can be used for T. gondii detection in blood, tissue, semen, urine and waste feed specimens. A total of 5462 blood specimens collected from pigs in 5 provinces and autonomous regions in southern China during 2016-2017 were assessed by the newly established GRA14 gene PCR method. The overall T. gondii infection rate was 18.9 % (1033/5462). According to the statistical analysis of different regions in China, the positive rates of swine toxoplasmosis from 2016 to 2017 were highest in the Shaanxi, Fujian and Guangdong areas, at 31.7 % (44/139), 21.9 % (86/391) and 18.8 % (874/4645), respectively. Specimens collected in 2017 had a higher positive rate (19.1 %) than those collected in 2016 (16.1 %). In addition, specimens collected in autumn (39.4 %), spring (22.8 %) and winter (18.2 %) had higher positive rates than those collected in summer (3.8 %). These results indicate that the new PCR method based on the T. gondii GRA14 gene has utility for the diagnosis of swine toxoplasmosis and can facilitate the diagnosis of toxoplasmosis in clinical laboratories.

Identification of Goose PKR Gene: Structure, Expression Profiling, and Antiviral Activity Against Newcastle Disease Virus.

Double-stranded RNA-dependent protein kinase (PKR) is an important antiviral IFN-stimulated gene (ISGs) that recognizes double-stranded RNA (dsRNA) and mediates inhibition of translation initiation and protein synthesis in various types of viral infection. In this study, the complete coding sequence (CDS) of goose PKR (goPKR) is identified and characterized. The open reading frame (ORF) of goPKR is 1668 bp, which encodes a polypeptide of 555 amino acids. The sequence identity results demonstrate that the goose PKR is most closely related to duck PKR gene, with nucleotide identities of 91.6%, whereas nucleotide identity of the goose PKR to chicken, human, and mouse PKR is 76.4%, 51.9%, and 52.0%, respectively. Interestingly, the deduced amino acid sequence of goose PKR contains 3 main structure domains, including 2 double-strand RNA-binding motif (dsRBM) domains and one serine/threonine protein kinase domain. This is similar to the chicken and mammals, whereas it is different from duck PKR protein, which contains only one dsRBM1 domain and one serine/threonine protein kinase domain. Quantitative real-time PCR analysis indicates that goose PKR mRNA is widely expressed in all sampled tissues. It is highly expressed in the blood, spleen, lung, and bursa of Fabricius and jejunum and is slightly expressed in heart, muscle, trachea, and brain. The results of confocal microscopy suggest that PKR-EGFP is mainly localized in the cytoplasm, and overexpression of goPKR protein significantly reduces Newcastle disease virus (NDV) replication (viral copies and viral titer) in goose embryo fibroblasts. These findings show that goose PKR is an important antiviral ISG, involved in the antiviral innate immune defense to NDV in geese.

[Gossypol decreases the expression of connexin 43 in Sertoli cells].

OBJECTIVE: To study the effect of gossypol on the expression of connexin 43 (CX43) in Sertoli cells. METHODS: TM4 Sertoli cells were cultured and treated with gossypol at the concentrations of 1.25, 2.5, 5 and 10 micromol/L for 6, 12, 24 and 48 hours. The cytotoxicity of gossypol was assessed by CCK-8 assay, and the expression of CX43 in the normal TM4 Sertoli cells and in those treated with different concentrations of gossypol for different times was detected by RT-PCR and immunofluorescence analysis. RESULTS: Semiquantitative RT-PCR and immunofluorescence analysis showed the expression of CX43 in the normal TM4 cells. At 24 hours of exposure to gossypol, the expression began to decrease gradually with the prolonging of time and the increasing concentration of gossypol (P < 0.05). CONCLUSION: Gossypol reduces the expression of CX43 in TM4 Sertoli cells, which might underlie the mechanism of its antifertility action.

Gap junctional protein connexin 43 in rat detrusor muscle with unstable bladder.

BACKGROUND: Unstable bladder is one of the common clinical dysfunctions of the lower urinary tract. Gap junctions (GJs) are the plaques of aqueous channels that facilitate electrical and metabolic communication between the intracellular compartments of adjacent cells, exchange of nutrients and ions between connected cells and transfer of electrical signals. In the present study we investigated the quantitative alterations of the GJ in the rat detrusor muscle and its functional changes related to the developing of unstable bladder (USB). METHODS: Thirteen female Wistar rats (study group) with obstructive unstable bladder as determined by urodynamic study and 10 sham-operated rats (control group) were sacrificed at 6 weeks after surgery. Cystometric investigation, and the content and distribution of the GJ protein connexin 43 (Cx43) in the detrusors which were taken from the bladder of the rats were studied by Western blot and laser confocal microscopy with a double label immunohistochemistry technique. RESULTS: The expression of Cx43 was found adjacent to the detrusor with the laser confocal microscopy. The Cx43 expression increased markedly in the study group (pixel density 29.5 +/- 13.9, staining size (17.9 +/- 8.8) microm2) compared with the control group (pixel density 14.2 +/- 2.2, staining size (5.7 +/- 3.1) microm2, P < 0.05). Western blot analysis demonstrated that Cx43 in the study group (the average gray level was 31.066) was significantly higher than in the control group (the average gray level was 11.701, P < 0.01). CONCLUSION: The increase of GJ leading to a intercellular excitatory communication is one of the important mechanisms related to developing unstable bladder.

Gossypol repressed the gap junctional intercellular communication between Sertoli cells by decreasing the expression of Connexin43.

Previous studies showed that gossypol could block the gap junctional intercellular communication (GJIC) between cultured cells. The present study was designed to investigate the effects of gossypol on the GJIC and the expression of connexin43 (Cx43) in the cultured cells. A Sertoli cell line, TM4, was treated with different concentrations of gossypol 1.25, 2.5, 5, and 10micromol/L for 6, 12, 24, and 48h. Cell viability was assessed with CCK-8 assay. GJIC in the cells was determined using the scrape loading and dye transfer (SLDT) assay; the expression of Cx43 was detected by RT-PCR, immunofluorescence and Western blot analysis. The SLDT assay showed gossypol significantly decreased GJIC between adjacent cells. RT-PCR, immunofluorescence and Western blot analyses demonstrated the expression of Cx43 in TM4 cells. The expression of Cx43 was gradually decreased with the increasing concentrations of gossypol, and the effect occurred as early as 6h after the treatment and continued until 48h. These results suggested that gossypol impaired GJIC by decrease of Cx43 expression in the cells, which is important for Sertoli cells to regulate spermatogenesis.